1. Field of the Invention
The invention relates to a storage system and a control method for the storage system, more particularly to a storage system in which storage subsystems are connected to each other can direct access received from a host computer to another storage subsystem, and a control method for that storage system.
2. Description of Related Art
A type of storage system in which a host computer and storage subsystems are mutually connected via a communication network and information is exchanged between the host computer and each storage subsystem is well known. JP-A-2006-85398 discloses, as a storage subsystem used in that type of storage system, a disk storage apparatus provided with a logical device, which is a data storage target device, a connection control unit, and a virtual logical unit has been proposed. That disk storage apparatus can switch connection between the virtual logical unit and the logical device in such a way that no change is observed by the control unit included in the host computer, when the disk storage apparatus is seen from the host computer.
Larger data storage capacity in storage subsystems is being required at present. Meanwhile, in the storage subsystem disclosed in JP-A-2006-85398, the target of virtualization is one internal disk storage device and one external disk storage device, but the technique disclosed there is not sufficient for integral management of a larger number of disk storage devices.
An object of the present invention is to integrally manage all storage subsystems belonging to one storage system by virtualizing those storage subsystems. Another object is to provide a storage system in which the host computer configuration definition does not have to be changed and only a change in storage subsystem configuration information is necessary.